1. Field of the Invention
The present invention relates generally to a door lock having a spring-projected slide bolt, a handle for retracting the bolt, and a key control for selectively permitting and preventing the handle from retracting the bolt. More particularly, the invention relates to a lock of this type including a key-controlled disconnect linkage for selectively drivingly connecting and disconnecting the handle and the bolt, whereby the handle is, at all times, freely movable between normal and operating positions, but is functional only when the key control is "unlocked" to enable the handle to retract the bolt.
While the present invention has particularly advantageous use in conjunction with flush-type door locks used on swinging doors of vehicles, industrial cabinets, electrical equipment enclosures and the like, principles of the invention are not limited in application to such uses.
2. Prior Art
Flush-type door locks including a body, a lock bolt slidably carried on the body, and an operating handle for moving the bolt relative to the body are well known. Normally the handle is in a flush or nested position when the bolt is projected. Bolt retraction is effected by pivoting the handle to an operating position. Locks of this type are well suited for use on swinging doors of vehicles such as trucks, on merchandise, tool and equipment cabinets, electrical equipment enclosures and the like.
Flush-type, paddle-handle door locks employing key-operated rotatable cams for selectively permitting and preventing unlocking movements of operating handles, and having spring-projected slide bolts, are described in U.S. Pat. Nos. 3,707,862, and 3,668,907 granted Jan. 2, 1973 and June 13, 1972, respectively, to John V. Pastva, Jr. An ornamental appearance employed in locks of this general type is illustrated in U.S. Pat. No. De. 230,132 issued Jan. 29, 1974 to John V. Pastva, Jr.
The provision of a handle disconnect feature in a door lock is desirable in that the presence of such a feature will lessen, if not totally eliminate, incidents of these locks being damaged by would-be intruders. Since the handles of most previously proposed door locks are restrained from moving when the locks are locked, it is common for would-be intruders to attempt to gain entry by applying excessive leverage force to the lock handles. Where handle disconnect features are provided, the lock handles may always be moved freely, but are functional to retract the bolt only when the locks are "unlocked." Locks having handle disconnect features can be made practically entry-proof short of the application of such forces as will totally destroy the locks.
Door locks employing various types of handle disconnect systems have been proposed. Prior proposals have, however, suffered from a variety of drawbacks including complexities of construction; failures to mount all of the operating parts of a lock on a single body member so that the resulting locks form compact, easy to install units; and inappropriately configured parts of sizes and shapes that prohibit installation of locks embodying such proposals in conventionally configured door lock mounting openings.
One prior proposal for a flush-type, paddle-handle door lock incorporating a handle disconnect feature has utilized a disconnect system having releasably engageable components located immediately behind the handle of the lock, at a location on the front side of the lock body. A problem with the "front-mounted" disconnect system utilized in this prior proposal is that access may be had to the disconnect member by a would-be intruder using an elongate tool such as a screwdriver, whereby the locking operation of the key control can be overcome. An advantage of front-mounted disconnect systems is that substantially conventionally-configured lock components may be utilized at locations behind the lock body, thereby minimizing the costs involved in adding a disconnect system to a conventional flush-mountable paddle-handle locks.
3. The Cross-Referenced Disconnect Patents
The present invention and the inventions described in the several referenced Disconnect Case represent the work products of a continuous and continuing development program which began nearly a decade ago.
The several handle disconnect systems described in the referenced Disconnect Case were developed by coworkers operating, in some instances independently, and in other instances jointly, as is reflected in the naming of sole and joint inventors. Many of the disconnect system features claimed in separate ones of the referenced Disconnect Patents were developed substantially concurrently.
Where a claim in one of the referenced Disconnect Patents is found to be generic to a development concept utilized in another of these patents, it should be understood that care has been taken to present the generic claim in the patent which describes the earliest development of a species that will support the generic claim. In this manner, a careful effort has been made to establish clear lines of demarcation among the claimed subjects matter of this and the several referenced Disconnect Patents. No two of these patents include claims of identical scope.